1. Field of the Invention
The present invention relates of a liquid transporting apparatus which transports liquid, and a method of manufacturing the liquid transporting apparatus.
2. Description of the Related Art
An ink-jet head which discharges ink from nozzles includes an actuator which imparts discharge energy to the ink. Actuator having various structures can be employed as such actuator. However, a piezoelectric actuator which includes a piezoelectric layer formed of a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), and which drives an object by using a deformation of the piezoelectric layer when an electric field acts on the piezoelectric layer, is widely known (for example, see U.S. Patent Application Publication No. US 2004/0223035 A1 corresponding to Japanese Patent Application Laid-open No. 2004-284109). The piezoelectric actuator described in U.S. Patent Application Publication No. US 2004/0223035 A1 includes a plurality of piezoelectric sheets adhered to one surface of a channel unit to cover an entire area in which a plurality of pressure chambers is formed, a plurality of individual electrodes which is arranged corresponding to the plurality of pressure chambers respectively on a surface of an uppermost piezoelectric sheet of the piezoelectric sheets, and common electrodes formed between the piezoelectric sheets. Further, when a drive voltage is applied to the individual electrodes, an electric field acts in a direction of thickness which is a polarization direction of the piezoelectric sheet sandwiched between the individual electrode and the common electrode, and the piezoelectric sheet is elongated in the direction of thickness and is contracted in a direction parallel to a plane. In this case, a vibration plate is deformed when of the piezoelectric sheet is deformed. Therefore, a volume of the pressure chamber is changed and a pressure is exerted on ink in the pressure chamber.
In the piezoelectric actuator described in U.S. Patent Application Publication No. US 2004/0223035 A1, the plurality of piezoelectric sheets are arranged to cover entirely the area in which the plurality of pressure chambers of the channel unit is formed (the area including partition wall sections which separate the pressure chambers). Therefore, when a portion of a piezoelectric sheet which overlaps with a certain pressure chamber is deformed, a so-called phenomenon of cross talk occurs in which this deformation is propagated to other portion of the piezoelectric sheet which overlaps with another pressure chamber adjacent to the pressure chamber, thereby deforming the another portion. In this case, depending on the number of pressure chambers which are driven at the same time (pressure is exerted on the ink inside the pressure chambers), an amount of deformation of each piezoelectric sheet which overlaps with each pressure chamber varies and there is a fluctuation in a velocity of an ink droplet, due to which a print quality is deteriorated. In this case, to suppress the cross talk, it is considered to form a groove or the like in the piezoelectric sheet so as to hinder the propagation of deformation. However, in this case, the piezoelectric sheet may become susceptible to chipping or a crack. In view of this problem, it is desirable to suppress to minimum the fluctuation of the velocity of the ink droplet which is caused due to the cross talk, by determining appropriately a value of each of the parameters of the piezoelectric actuator such as a thickness of the piezoelectric sheet and a thickness of an adhesive layer which adheres the piezoelectric sheet and the channel unit.